1. Field of the Invention
The present invention relates to a radial line dial plate and an automobile meter provided with the radial line dial plate.
2. Description of the Related Art
For a dial plate to be used in, for example, automobile meters under severe environmental conditions due to heat, vibration, or the like, there is known a dial plate produced by a metal such as stainless steel or aluminum such that the automobile meters have metallic feeling, high-grade feeling, or decorativeness (see Japanese Patent Application Laid-open No. 2003-4495 and the like). In the dial plate disclosed in the literature, a plate member is made of a metal and radial line marks are applied to the surface thereof.
Radial line marking is performed by marking of fine grooves on a metallic surface by a brush or the like, and radial gloss occurs on the surface of a metallic dial plate by external light reflected onto the grooves. In the marking by the brush, the brush is stroked in a direction closer to the center of the metallic dial plate, and the fine grooves are formed on the surface. At the same time, the dial plate is rotated. That is, after the brush is stroked, the dial plate is rotated at very small angle, and the subsequent stroke is performed.
In the dial plate made of the metal, radial line mark treatment is required to be performed for each sheet of metal plates by a brush, and there are problems in terms of obtaining a uniform quality and in terms of manufacturing costs. In addition, since the dial plate is made of the metal, it is heavy in weight, which is disadvantageous to weight reduction in vehicle, especially.
Therefore, a metallic-tone dial plate has been proposed in which metallic feeling is created using a transparent synthetic resin such as an acrylic resin or polycarbonate (for example, see Japanese Patent Application Laid-open No. 2013-40773). In the metallic-tone dial plate disclosed in Japanese Patent Application Laid-open No. 2013-40773, a dial plate body is molded by a synthetic resin and is provided with a smooth surface and a concave-convex surface on the surface thereof. Then, a metal layer is formed on the smooth surface and the concave-convex surface of the dial plate body by surface treatment such as vapor deposition, plating, or painting. Thus, it is possible to produce the metallic-tone dial plate formed with the smooth surface and the concave-convex surface without processing the metallic plate and to provide the dial plate, which can create the metallic feeling, at a low cost.
In a conventional marking method, however, a plurality of marks corresponding to a width of the brush are applied at the same time with a single stroke. The marking due to the previous stroke is marking on a straight line directed to the center of the dial plate, which is the same as in the next stroke. Therefore, numerous intersection points appear through the marking of the previous stroke and the next stroke. In the radial line marks in which numerous intersection points appear, white gloss appears and thus feeling of metal working is reduced. In addition, as described above, when the marking due to the fine grooves is performed for each sheet of metallic dial plates by the brush or the like, it is not entirely suited to mass production of the same radial line pattern, and material costs and manufacturing costs also increase to high cost. Furthermore, the metallic dial plate is heavy in weight, which is disadvantageous to weight reduction in the case of being used in automobile meters for a vehicle, especially.
Furthermore, in the above-described metallic-tone dial plate using the synthetic resin, a dial plate body is integrally molded using a molding die. A molding die portion for molding the concave-convex surface (die mark-molding-face) can be finished to be a concave-convex surface by embossing. Alternatively, the die mark-molding-face may be provided with spin hairline-shaped irregularities, and it is considered that the embossing may not be performed when roughness of a polished surface is rough more than of the smooth surface.
However, if the die mark-molding-face is formed by a processing method such as a brush process (hairline), embossing, or polishing, when a plurality of molding dies are produced, a problem occurs in that metallic tone differs for each molding die.